IMPORTANT: The CCK2 Wizard is a legacy extension so it can only be installed on Firefox 56 and below. You also must turn off add-on signing by going to about:config and setting xpinstall.signatures.required to false.
The Autoconfig file it generates will work with the Firefox ESR and with any version Firefox through 62 on Rapid Release.
Starting with Firefox 62, AutoConfig is sandboxed to its original API by default.
There is a preference (general.config.sandbox_enabled) that can be set to false to allow the CCK2 to work. (I set that pref in the latest version of the CCK2.)
This preference will be removed on rapid release once a sufficient amount of CCK2 functionality has been moved into Firefox via the GPO and the policy engine. That could happen as soon as Firefox 64.
AutoConfig will NOT be sandboxed on the ESR.
I strongly recommend investigating the new policy engine and GPO support on Firefox as a replacement for CCK2. You can get more information here.